Integrins are a super-family of cell surface adhesion receptors, which control the attachment of cells with the solid extracellular environment, both to the extracellular matrix (ECM), and to other cells. Adhesion is of fundamental importance to a cell; it provides anchorage, cues for migration, and signals for growth and differentiation. Integrins are directly involved in numerous normal and pathological conditions, and as such are primary targets for therapeutic intervention. Integrins are integral transmembrane proteins, heterodimers, whose binding specificity depends on which of the 14 α-chains are combined with which of the 8 β-chains. The integrins are classified in four overlapping subfamilies, containing the β1, β2, β3 or αv chains. A cell may express several different integrins from each subfamily. In the last several decades, it has been shown that integrins are major receptors involved in cell adhesion, and so may be a suitable target for therapeutic intervention. Integrin αvβ3 regulates cell growth and survival, since ligation of this receptor can, under some circumstances, induce apoptosis in tumor cells. Disruption of cell adhesion with anti-αvβ3 antibodies, RGD peptides, and other integrin antagonists has been shown to slow tumor growth.